This invention relates to diode-pumped optical amplifiers.
A conventional injection laser diode emits light from both the front end facet and the rear end facet. Normally however it is only the light emitted from the front facet that is made available for use in the world outside the laser package, while that emitted from the rear facet is employed internally of the package for monitoring purposes. In certain types of laser chip the construction is designed such that much more light is emitted from the front facet than from the rear, but the most basic design provides substantially the same power from both facets. An injection laser diode has a number of advantages as an optical source for pumping an optical amplifier, but the fact that much of its power is not used for pumping, because it is emitted from the rear facet of the diode, is not one of those advantages.